This application claims the benefit of Korean Application No. 2002-33221, filed Jun. 14, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates generally to an air conditioning apparatus and control method thereof, which has an inverter-type compressor and a two-stage variable-capacity compressor.
2. Description of the Related Art
Generally, a single air conditioning apparatus in which one indoor unit is connected to one outdoor unit does not have a large indoor air conditioning load (required capacity). Thus, in the single air conditioning apparatus, a fixed-capacity compressor is installed in the outdoor unit.
In contrast, a multi-unit air conditioning apparatus in which a plurality of indoor units are connected to one outdoor unit is designed such that each of the indoor units independently copes with an air conditioning load of a corresponding indoor space. In the multi-unit air conditioning apparatus, since the air conditioning loads of the respective indoor units are different and varied at any time, a variable-capacity compressor is installed in the outdoor unit. Accordingly, a flow of refrigerant is controlled by ascertaining the loads and operating states of the indoor units using communications between each of the indoor units and the outdoor unit. Typically, the variable-capacity compressor is controlled by a microcomputer of the outdoor unit. The microcomputer checks air conditioning requirements with respect to a corresponding indoor space, a temperature condition of the corresponding indoor space, etc., on the basis of information received from each of the indoor units, and controls a capacity of the compressor according to the checked information.
However, since the conventional multi-unit air conditioning apparatus employs a construction in which the plurality of indoor units are connected to the one outdoor unit, the compressor installed in the outdoor unit must be designed to endure a maximum indoor air conditioning load. Further, in order for the compressor to endure the maximal indoor air conditioning load, significant difficulty arises in production of the compressor. That is, a plurality of performance tests must be carried out so as to increase the capacity of the compressor. A high-capacity compressor produced by the above process is problematic in that it is very expensive, relative to a conventional compressor.
Conventionally, a variable-capacity compressor and a fixed-capacity compressor are mixed to cope with indoor air conditioning loads in consideration of the above problem. As shown in FIG. 1, a compressor 10 to operate at a capacity varied according to a frequency of an inverter circuit, and a fixed-capacity compressor 20 to operate at a constant capacity are connected in parallel with each other. Further, an outdoor unit microcomputer (not shown) controls capacities of the compressors 10 and 20 according to indoor air conditioning loads (required capacities) received from respective indoor units.
As shown in FIG. 2, if the indoor air conditioning loads are 0 to 50%, the outdoor unit microcomputer controls the capacity of the compressor 10. In this case, the microcomputer controls the capacity of the compressor 10 by varying the frequency outputted to the compressor 10 from the inverter circuit within a predetermined range R1 according to the indoor air conditioning load received from the respect indoor units. Further, if the indoor air conditioning loads are 50 to 100%, the outdoor unit microcomputer controls the capacities of the compressors 10 and 20. In this case, the microcomputer copes with an insufficient capacity by controlling the capacity of the inverter-type compressor 10 within a predetermined range R2 after activating the fixed-capacity compressor 20.
However, if the conventional multi-unit air conditioning apparatus as described above is applied in facilities such as large buildings, the capacity which is usually covered by a variable-capacity compressor inevitably becomes large. It is difficult to produce a high-capacity compressor such as the variable-capacity compressor as an independent device. Further, a cost of the high-capacity compressor is expensive even though it may be produced as an independent device, thus causing an economic burden by increasing a price of the compressor.
Therefore, in the multi-unit air conditioning apparatus, a method is required to effectively cope with a large-scale indoor air conditioning load and accommodate requirements for a large-scale air conditioning capacity while using a conventional compressor.
Accordingly, it is an aspect of the present invention to provide an air conditioning apparatus and control method thereof, in which an inverter-type compressor and a two-stage variable-capacity compressor are connected in parallel with each other to cope with indoor air conditioning loads inexpensively.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other aspects of the present invention are achieved by providing an air conditioning apparatus including a first compressor, a second compressor connected in parallel with the first compressor and controlled to operate at one of a minimum capacity and a maximum capacity, and a control unit to control capacities of the first and second compressors such that a total capacity of the first and second compressors is linearly controlled according to indoor air conditioning loads.
The foregoing and other aspects of the present invention are achieved by providing an air conditioning apparatus including a plurality of indoor units and an outdoor unit connected to the plurality of indoor units. The outdoor unit includes a first compressor, a second compressor connected in parallel with the first compressor and controlled to operate at one of a minimum capacity and a maximum capacity, and an outdoor control unit to control capacities of the first and second compressors such that a total capacity of the first and second compressors is linearly controlled according to indoor air conditioning loads required by the indoor units.
The foregoing and other aspects of the present invention are achieved by providing a method of controlling an air conditioning apparatus. The air conditioning apparatus has a plurality of indoor units connected to an outdoor unit, which includes a first compressor to control a capacity thereof according to a frequency of an inverter circuit, and a second compressor to operate at one of a minimum capacity and a maximum capacity. The method includes calculating an air conditioning capacity required by corresponding indoor units and controlling capacities of the first and second compressors such that a total capacity of the first and second compressors is linearly controlled according to the calculated required air conditioning capacity. A maximum capacity of the first compressor is equal to the minimum capacity of the second compressor, and the maximum capacity of the second compressor is two or more times greater than the minimum capacity of the second compressor.
The foregoing and other aspects of the present invention are achieved by providing an apparatus including two compressors connected in parallel with each other. One of the compressors is an inverter-type compressor which linearly controls a capacity thereof, and the other is a two-stage variable-capacity compressor which has a relatively large capacity and operates at two different capacities.